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https://github.com/LadybirdBrowser/ladybird.git
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3c1ef744f6
This adds the ability to implement custom null states that allow storing state in null pointers.
352 lines
10 KiB
C++
352 lines
10 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/LogStream.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/StdLibExtras.h>
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#include <AK/Traits.h>
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#include <AK/Types.h>
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namespace AK {
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template<typename T>
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class OwnPtr;
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template<typename T>
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struct RefPtrTraits {
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static T* as_ptr(FlatPtr bits)
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{
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return (T*)bits;
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}
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static FlatPtr as_bits(T* ptr)
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{
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return (FlatPtr)ptr;
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}
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static bool is_null(FlatPtr bits)
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{
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return !bits;
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}
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static constexpr FlatPtr default_null_value = 0;
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typedef std::nullptr_t NullType;
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};
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template<typename T, typename PtrTraits>
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class RefPtr {
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template<typename U, typename P>
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friend class RefPtr;
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public:
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enum AdoptTag {
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Adopt
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};
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RefPtr() { }
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RefPtr(const T* ptr)
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: m_bits(PtrTraits::as_bits(const_cast<T*>(ptr)))
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{
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ref_if_not_null(const_cast<T*>(ptr));
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}
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RefPtr(const T& object)
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: m_bits(PtrTraits::as_bits(const_cast<T*>(&object)))
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{
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T* ptr = const_cast<T*>(&object);
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ASSERT(ptr);
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ASSERT(!ptr == PtrTraits::is_null(m_bits));
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ptr->ref();
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}
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RefPtr(AdoptTag, T& object)
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: m_bits(PtrTraits::as_bits(&object))
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{
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ASSERT(&object);
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ASSERT(!PtrTraits::is_null(m_bits));
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}
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RefPtr(RefPtr&& other)
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: m_bits(other.leak_ref_raw())
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{
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}
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ALWAYS_INLINE RefPtr(const NonnullRefPtr<T>& other)
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: m_bits(PtrTraits::as_bits(const_cast<T*>(other.ptr())))
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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PtrTraits::as_ptr(m_bits)->ref();
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}
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template<typename U>
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ALWAYS_INLINE RefPtr(const NonnullRefPtr<U>& other)
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: m_bits(PtrTraits::as_bits(const_cast<U*>(other.ptr())))
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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PtrTraits::as_ptr(m_bits)->ref();
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}
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template<typename U>
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ALWAYS_INLINE RefPtr(NonnullRefPtr<U>&& other)
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: m_bits(PtrTraits::as_bits(&other.leak_ref()))
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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}
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template<typename U, typename P = RefPtrTraits<U>>
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RefPtr(RefPtr<U, P>&& other)
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: m_bits(other.leak_ref_raw())
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{
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}
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RefPtr(const RefPtr& other)
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: m_bits(PtrTraits::as_bits(const_cast<T*>(other.ptr())))
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{
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ref_if_not_null(const_cast<T*>(other.ptr()));
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}
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template<typename U, typename P = RefPtrTraits<U>>
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RefPtr(const RefPtr<U, P>& other)
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: m_bits(PtrTraits::as_bits(const_cast<U*>(other.ptr())))
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{
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ref_if_not_null(const_cast<U*>(other.ptr()));
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}
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ALWAYS_INLINE ~RefPtr()
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{
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clear();
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#ifdef SANITIZE_PTRS
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if constexpr (sizeof(T*) == 8)
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m_bits = 0xe0e0e0e0e0e0e0e0;
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else
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m_bits = 0xe0e0e0e0;
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#endif
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}
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RefPtr(std::nullptr_t) { }
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template<typename U>
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RefPtr(const OwnPtr<U>&) = delete;
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template<typename U>
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RefPtr& operator=(const OwnPtr<U>&) = delete;
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template<typename U>
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void swap(RefPtr<U, PtrTraits>& other)
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{
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::swap(m_bits, other.m_bits);
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}
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ALWAYS_INLINE RefPtr& operator=(RefPtr&& other)
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{
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RefPtr tmp = move(other);
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swap(tmp);
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return *this;
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}
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template<typename U>
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ALWAYS_INLINE RefPtr& operator=(RefPtr<U, PtrTraits>&& other)
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{
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RefPtr tmp = move(other);
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swap(tmp);
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return *this;
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}
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template<typename U>
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ALWAYS_INLINE RefPtr& operator=(NonnullRefPtr<U>&& other)
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{
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RefPtr tmp = move(other);
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swap(tmp);
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ASSERT(!PtrTraits::is_null(m_bits));
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return *this;
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}
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ALWAYS_INLINE RefPtr& operator=(const NonnullRefPtr<T>& other)
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{
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RefPtr tmp = other;
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swap(tmp);
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ASSERT(!PtrTraits::is_null(m_bits));
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return *this;
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}
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template<typename U>
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ALWAYS_INLINE RefPtr& operator=(const NonnullRefPtr<U>& other)
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{
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RefPtr tmp = other;
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swap(tmp);
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ASSERT(!PtrTraits::is_null(m_bits));
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return *this;
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}
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ALWAYS_INLINE RefPtr& operator=(const RefPtr& other)
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{
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RefPtr tmp = other;
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swap(tmp);
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return *this;
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}
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template<typename U>
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ALWAYS_INLINE RefPtr& operator=(const RefPtr<U>& other)
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{
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RefPtr tmp = other;
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swap(tmp);
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return *this;
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}
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ALWAYS_INLINE RefPtr& operator=(const T* ptr)
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{
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RefPtr tmp = ptr;
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swap(tmp);
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return *this;
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}
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ALWAYS_INLINE RefPtr& operator=(const T& object)
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{
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RefPtr tmp = object;
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swap(tmp);
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return *this;
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}
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RefPtr& operator=(std::nullptr_t)
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{
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clear();
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return *this;
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}
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ALWAYS_INLINE void clear()
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{
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unref_if_not_null(PtrTraits::as_ptr(m_bits));
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m_bits = PtrTraits::default_null_value;
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}
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bool operator!() const { return PtrTraits::is_null(m_bits); }
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[[nodiscard]] T* leak_ref()
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{
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FlatPtr bits = exchange(m_bits, PtrTraits::default_null_value);
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return !PtrTraits::is_null(bits) ? PtrTraits::as_ptr(bits) : nullptr;
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}
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NonnullRefPtr<T> release_nonnull()
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *leak_ref());
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}
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ALWAYS_INLINE T* ptr() { return !PtrTraits::is_null(m_bits) ? PtrTraits::as_ptr(m_bits) : nullptr; }
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ALWAYS_INLINE const T* ptr() const { return !PtrTraits::is_null(m_bits) ? PtrTraits::as_ptr(m_bits) : nullptr; }
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ALWAYS_INLINE T* operator->()
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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return PtrTraits::as_ptr(m_bits);
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}
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ALWAYS_INLINE const T* operator->() const
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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return PtrTraits::as_ptr(m_bits);
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}
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ALWAYS_INLINE T& operator*()
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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return *PtrTraits::as_ptr(m_bits);
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}
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ALWAYS_INLINE const T& operator*() const
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{
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ASSERT(!PtrTraits::is_null(m_bits));
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return *PtrTraits::as_ptr(m_bits);
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}
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ALWAYS_INLINE operator const T*() const { return PtrTraits::as_ptr(m_bits); }
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ALWAYS_INLINE operator T*() { return PtrTraits::as_ptr(m_bits); }
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operator bool() { return !PtrTraits::is_null(m_bits); }
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bool operator==(std::nullptr_t) const { return PtrTraits::is_null(m_bits); }
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bool operator!=(std::nullptr_t) const { return !PtrTraits::is_null(m_bits); }
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bool operator==(const RefPtr& other) const { return m_bits == other.m_bits; }
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bool operator!=(const RefPtr& other) const { return m_bits != other.m_bits; }
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bool operator==(RefPtr& other) { return m_bits == other.m_bits; }
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bool operator!=(RefPtr& other) { return m_bits != other.m_bits; }
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bool operator==(const T* other) const { return PtrTraits::as_ptr(m_bits) == other; }
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bool operator!=(const T* other) const { return PtrTraits::as_ptr(m_bits) != other; }
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bool operator==(T* other) { return PtrTraits::as_ptr(m_bits) == other; }
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bool operator!=(T* other) { return PtrTraits::as_ptr(m_bits) != other; }
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bool is_null() const { return PtrTraits::is_null(m_bits); }
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template<typename U = T, typename EnableIf<IsSame<U, T>::value && !IsNullPointer<typename PtrTraits::NullType>::value>::Type* = nullptr>
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typename PtrTraits::NullType null_value() const
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{
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// make sure we are holding a null value
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ASSERT(PtrTraits::is_null(m_bits));
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return PtrTraits::to_null_value(m_bits);
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}
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template<typename U = T, typename EnableIf<IsSame<U, T>::value && !IsNullPointer<typename PtrTraits::NullType>::value>::Type* = nullptr>
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void set_null_value(typename PtrTraits::NullType value)
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{
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// make sure that new null value would be interpreted as a null value
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FlatPtr bits = PtrTraits::from_null_value(value);
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ASSERT(PtrTraits::is_null(bits));
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clear();
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m_bits = bits;
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}
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private:
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[[nodiscard]] FlatPtr leak_ref_raw()
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{
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return exchange(m_bits, PtrTraits::default_null_value);
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}
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FlatPtr m_bits { PtrTraits::default_null_value };
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};
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template<typename T, typename PtrTraits = RefPtrTraits<T>>
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inline const LogStream& operator<<(const LogStream& stream, const RefPtr<T, PtrTraits>& value)
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{
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return stream << value.ptr();
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}
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template<typename T>
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struct Traits<RefPtr<T>> : public GenericTraits<RefPtr<T>> {
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using PeekType = const T*;
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static unsigned hash(const RefPtr<T>& p) { return ptr_hash(p.ptr()); }
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static bool equals(const RefPtr<T>& a, const RefPtr<T>& b) { return a.ptr() == b.ptr(); }
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};
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template<typename T, typename U>
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inline NonnullRefPtr<T> static_ptr_cast(const NonnullRefPtr<U>& ptr)
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{
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return NonnullRefPtr<T>(static_cast<const T&>(*ptr));
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}
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template<typename T, typename U, typename PtrTraits = RefPtrTraits<T>>
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inline RefPtr<T> static_ptr_cast(const RefPtr<U>& ptr)
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{
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return RefPtr<T, PtrTraits>(static_cast<const T*>(ptr.ptr()));
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}
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}
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using AK::RefPtr;
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using AK::static_ptr_cast;
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